The invention relates to a high impact resistant tool that may be used in machinery such as crushers, picks, grinding mills, roller cone bits, rotary fixed cutter bits, earth boring bits, percussion bits or impact bits, and drag bits. More particularly, the invention relates to inserts comprised of a carbide substrate with a nonplanar interface and an abrasion resistant layer of super hard material affixed thereto using a high-pressure, high-temperature (HPHT) press apparatus. Such inserts typically include a super hard material layer or layers formed under HPHT conditions. The layers are usually formed in a press apparatus designed to create HPHT conditions and are cemented to a carbide substrate containing a metal binder or catalyst such as cobalt. The carbide substrate is often softer than the super hard material to which it is bonded. Some examples of super hard materials that HPHT presses may produce and sinter include cemented ceramics, polycrystalline diamond, and cubic boron nitride. A cutting element or insert is normally fabricated by placing a carbide substrate into a container or cartridge with a layer of diamond crystals or grains loaded into the cartridge adjacent one face of the carbide substrate. A number of such cartridges are typically loaded into a reaction cell and placed in the HPHT press apparatus. The carbide substrates and adjacent diamond crystal layers are then compressed under HPHT conditions which promotes a sintering of the diamond grains to form a polycrystalline diamond structure. As a result, the diamond grains become mutually bonded to form a diamond layer over the carbide substrate interface. The diamond layer is also bonded to the carbide substrate interface.
Such inserts are often subjected to intense forces, torques, vibration, high temperatures and temperature differentials during operation. As a result, stresses within the structure may begin to form. Drill bits for example may exhibit stresses aggravated by drilling anomalies during well boring operations such as bit whirl or bounce often resulting in spalling, delamination or fracture of the super hard abrasive layer or the substrate thereby reducing or eliminating the cutting elements efficacy and decreasing overall drill bit wear life. The superhard material layer of an insert sometimes delaminates from the carbide substrate after the sintering process as well as during percussive and abrasive use. Damage typically found in percussive and drag bits may be a result of shear failures, although non-shear modes of failure are not uncommon. The interface between the superhard material layer and substrate is particularly susceptible to non-shear failure modes due to inherent residual stresses.
U.S. Pat. No. 5,544,713 by Dennis, which is herein incorporated by reference for all that it contains, discloses a cutting element which has a metal carbide stud having a conic tip formed with a reduced diameter hemispherical outer tip end portion of said metal carbide stud. The tip is shaped as a cone and is rounded at the tip portion. This rounded portion has a diameter which is 35-60% of the diameter of the insert.
U.S. Pat. No. 6,408,959 by Bertagnolli et al., which is herein incorporated by reference for all that it contains, discloses a cutting element, insert or compact which is provided for use with drills used in the drilling and boring of subterranean formations.
U.S. Pat. No. 6,484,826 by Anderson et al., which is herein incorporated by reference for all that it contains, discloses enhanced inserts formed having a cylindrical grip and a protrusion extending from the grip.
U.S. Pat. No. 5,848,657 by Flood et al., which is herein incorporated by reference for all that it contains, discloses domed polycrystalline diamond cutting element wherein a hemispherical diamond layer is bonded to a tungsten carbide substrate, commonly referred to as a tungsten carbide stud. Broadly, the inventive cutting element includes a metal carbide stud having a proximal end adapted to be placed into a drill bit and a distal end portion. A layer of cutting polycrystalline abrasive material disposed over said distal end portion such that an annulus of metal carbide adjacent and above said drill bit is not covered by said abrasive material layer.
U.S. Pat. No. 4,109,737 by Bovenkerk, which is herein incorporated by reference for all that it contains, discloses a rotary bit for rock drilling comprising a plurality of cutting elements mounted by inference-fit in recesses in the crown of the drill bit. Each cutting element comprises an elongated pin with a thin layer of polycrystalline diamond bonded to the free end of the pin.
U.S. Patent Application Serial No. 2001/0004946 by Jensen, although now abandoned, is herein incorporated by reference for all that it discloses. Jensen teaches that a cutting element or insert with improved wear characteristics while maximizing the manufacturability and cost effectiveness of the insert. This insert employs a superabrasive diamond layer of increased depth and by making use of a diamond layer surface that is generally convex.